Helmet rear portion



FIG. 1 is a front and left side perspective view of a helmet rear portion showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The structure shown in broken lines forms no part of the claimed design. 

The ornamental design for a helmet rear portion, as shown and described. 